The civil rights issue that has embarrassed the Reagan administration the last two weeks--tax-exempt status for racially discriminatory private schools--has been around for years, but did not really heat up until a federal court forced the Carter administration to propose tougher enforcement rules in 1978.

The Internal Revenue Service in theory has denied tax-exempt status to such schools since 1970, but its early enforcement rules required only that a school file a declaration of nondiscrimination in order to qualify for exemption. Most schools did so. In 1979, the U.S. Commission on Civil Rights estimated that 3,500 private schools had been started or greatly expanded after desegregation of public schools in their districts. Only about 110 have lost the government benefit.

Jerome Kurtz, the commissioner of the Internal Revenue Service during the Carter administration, recalled last week that the only schools that had had exemptions lifted early on were those that flatly refused to make the nondiscrimination statement.

Kurtz has said that the IRS was first pushed to promulgate national rules on the subject after black parents in Mississippi won an injunction against tax-exempt status for discriminatory schools in that state in a 1970 court case called Green v. Connally.

It was then pushed to propose tougher rules in 1978 by the threat of further court action in the Green case.

Kurtz said he was "infuriated" when he heard President Reagan say at last Tuesday's press conference that he had moved to revoke even the undemanding original IRS rules because they had "no basis in law" and he wanted to stop the service from "determining national social policy all by itself."

"It wasn't bureaucrats running amok" who proposed the first rules in 1971, Kurtz said. "It was bureaucrats trying to stay out of jail."

The tougher rules Kurtz proposed in 1978, which would make a school suspect if the minority percentage in its student body was not at least a fifth as large as the minority percentage in the community, brought on a firestorm of protest from fundamentalist Christian and some other religious schools, which said that First Amendment religious freedoms were in peril.

The IRS received 150,000 letters on the proposed rules, the most it has ever received in response to such an issue. And even though IRS revised the proposed rules in early 1979, opponents in Congress attached riders to appropriations bills blocking their implementation.

Rep. Robert K. Dornan (R-Calif.), sponsor of one rider, summed up the feeling of many in Congress when he said during the debate: "They IRS officials were set up to collect revenue, not to engage in social engineering across the country."

The Green lawyers went back to court, however. In May, 1980, U.S. District Court Judge George L. Hart raised the standards that Mississippi schools had to meet to prove they were not discriminating. His new standards were similar to the ones IRS was being blocked by Congress from applying across the country.

At the same time, civil rights lawyers in Hart's court were trying, in a case now known as Wright v. Regan, to have the revised Green standards applied nationwide. In effect they were trying an end-run around Congress, to have the courts require the IRS to do what Congress would not let it.

Hart ruled that the new plaintiffs, black parents in other states, did not have standing to sue because they had not been injured by the alleged discriminatory policy. But a U.S. Circuit Court of Appeals panel here reversed him, and that case is now before the Supreme Court.

Both the Carter and Reagan administrations have supported Hart in arguing that the Wright plaintiffs do not have standing.

While civil rights groups were pressing in court to strengthen the IRS rules, affected schools were pressing to kill them. Suits brought on grounds of religious freedom by two such schools, Bob Jones University of Greenville, S. C., and Goldsboro Christian Schools of North Carolina, had reached the Supreme Court. The Reagan administration's policy reversal, its original announcement that it would no longer deny tax-exempt status to any schools, came in connection with these cases.

The reversal created its own storm of protest, and now the administration says it wants Congress to pass a bill denying tax-exempt status to discriminating schools; meanwhile, the IRS will mark time on the issue.

In the brief the Justice Department filed with the Supreme Court in the Bob Jones case before the policy reversal, government lawyers argued that lower courts had been right in denying the two schools tax-exempt status despite the schools' First Amendment claims.

But it went on to say the IRS was meeting "substantial resistance" from church-related schools. The brief noted that 12 of 29 church-operated schools the IRS had had to investigate under the Green case had raised First Amendment arguments as a "bar to compliance with the Service's request for the information necessary to complete its investigation."

Justice urged then that the Supreme Court take the case because the earlier court rulings had been "inadequate to avoid unseemly confrontations with religious claims." The congressional attitude was also a problem, the brief said.